Are there crowd-sourced websites for travel bucket lists?

I'm in the early stages of planning a three week trip to Japan, and I'm still working out where to go. There's a couple of things on my "to do" list, but I want to find out if there's any activities or attractions that I'd be kicking myself for not seeing if this were my last trip to Japan.

I've done a bit of googling for individuals' bucket lists, but it can be frustrating when the same item gets repeated on multiple lists, such as the Kanamara Matsuri being listed on http://thetravellingdork.com/2012/04/bucket-list-20-things-to-do-when-i-get-to-japan/ and http://www.blakeinjapan.com/japan-bucket-list/

Are there any good web 2.0 style sites, where there is information contributed by several people, without the same attractions being listed multiple times?

Ideally, when appropriate the information would be organized by type of activity and not merely by an individual attraction, so you'd be able to see "See a kabuki play" as an item, rather than having all the different theatres clutter up the list.